check dependencies

Ai/Ocr/Tesseract/TesseractOcr.php

@@ -102,14 +102,22 @@ final class TesseractOcr
             . ' -l ' . \implode('+', $languages)
         );
 
-        $parsed = \file_get_contents($temp . '.txt');
+        $filepath = \is_file($temp . '.txt')
+            ? $temp . '.txt'
+            : $temp;
+
+        if (!\is_file($filepath)) {
+            return '';
+        }
+
+        $parsed = \file_get_contents($filepath);
         if ($parsed === false) {
             return '';
         }
 
         // @todo: auto flip image if x% of text are garbage words?
 
-        \unlink($temp);
+        \unlink($filepath);
 
         return \trim($parsed);
     }

tests/Ai/Ocr/Tesseract/TesseractOcrTest.php

@@ -24,6 +24,18 @@ use phpOMS\Image\Thresholding;
  */
 final class TesseractOcrTest extends \PHPUnit\Framework\TestCase
 {
+    /**
+     * {@inheritdoc}
+     */
+    protected function setUp() : void
+    {
+        if (!\is_file('/usr/bin/tesseract')) {
+            $this->markTestSkipped(
+              'Couldn\'t find tesseract'
+            );
+        }
+    }
+
     private function outputTest(string $name, float $m1, float $m2) : void
     {
         if (false) {